Hypohalogenation of gem-diphosphonate esters and phosphonoacetate esters

ABSTRACT

A PROCESS FOR THE PRODUCTION OF MONO- AND DIHALOGENEATED GEM-DIPHOSPHONATE ESTERS (C3-C8) AND MONOAND DIHALOGENTAED PHOSPHONOACETATE ESTERS (C5-C7) IS DISCLOSED. DIBROMINATED AND DIIODATED GEM-DIPHOSPHONATE ESTERS CONTAINING ALKYL GROUPS HAVING THREE TO EIGHT CARBON ATOMS, DICHLORINATED GEM-DIPHOSPHONATE ESTERS CONTAINING ALKYL GROUPS HAVING FROM 7 TO 8 CARBON ATOMS, AND MONOHALOGENATED GEM-DIPHOSPHONATE ESTERS CONTAINING ALKYL GROUPS HAVING FROM 7 TO 8 CARBON ATOMS, AS NOVEL COMPOUNDS, ARE ALSO DISCLOSED. THE GEM-DIPHOSPHONATE ESTERS ARE USEFUL AS INTERMEDIATES IN THE SYNTHESIS OF DETERGENT BUILDERS AND AS EXTREME PRESSURE AND ANTI-WEAR ADDITIVIES IN LUBRICANT CMPOSITIONS. THE PHOSPHONOACETATE ESTERS ARE USEFUL AS EXTREME PRESSURE AND ANTI-WEAR ADDITIVIES IN LUBRICANT CMPOSITIONS.

United States Patent 3,772,412 HYPOHALOGENATION OF GEM-DIPHOSPHON ATE ESTERS AND PHOSPHONOACETATE ESTERS Oscar T. Quimby, Colerain Township, Hamilton County,

Ohio, and James B. Prentice, Batesville, Ind., assignors to The Procter & Gamble Company, Cincinnati, Ohio No Drawing. Continuation of application Ser. No.

770,782, Oct. 25, 1968, which is a continuation-inpart of application Ser. No. 587,417, Oct. 18, 1966, both now abandoned. This application June 28, 1971, Ser. No. 157,703 I Int. Cl. C07f 9/40 U.S. Cl. 260-932 14 Claims ABSTRACT OF THE DISCLOSURE A process for the production of monoand dihalogenated gem-diphosphonate esters (C -C and monoand dihalogenated phosphonoacetate esters (C -C is disclosed. Dibrominated and diiodated gem-diphosphonate esters containing alkyl groups having three to eight carbon atoms, dichlorinated gem-diphosphonate esters containing alkyl groups having from 7 to 8 carbon atoms, and monohalogenated gem-diphosphonate esters containing alkyl groups having from 7 to 8 carbon atoms, as novel compounds, are also disclosed. The gem-diphosphonate esters are useful as intermediates in the synthesis of detergent builders and as extreme pressure and anti-wear additives in lubricant compositions. The phosphonoacetate esters are useful as extreme pressure and anti-wear additives in lubricant compositions.

CROSS-REFERENCE This application is a continuation of Ser. No. 770,782, filed Oct. 25, 1968 and now abandoned, which in turn is a continuation-in-part of Ser. No. 587,417, filed Oct. 18, 1966 and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a process for the production of monoand dihalogenated gem-diphosphonate esters (C C and monoand dihalogenated phosphonoacetate esters (C -C and to certain novel dichloro-, dibromo-, diiodo-, and monohalo-gern-diphosphonate esters. It relates specifically to a process for the production of monoand dihalogenated gem-diphosphonate esters which are valuable intermediates in the synthesis of detergent builders and as extreme pressure and antiwear additives for use in lubricant compositions and to the production of monoand dihalogenated phosphonoacetate esters useful as extreme pressure additives for use in lubricant compositions. (The term diphosphonate esters, as used hereinafter, is intended to include the monoand dihalogenated gem-diphosphonate esters as a group and the term phosphonoacetate esters, as used hereinafter, is intended to include dihalogenated phosphonoacetate esters. The'term esters, as used herein, is intended to include both the diphosphonate esters and the phosphonoacetate esters.)

The use of builders as adjuncts to soap and synthetic detergents and the properties demonstrated by their use in improving detergency levels is well known. Among the satisfactory builders for use with soap and synthetic detergents which can be obtained from the compounds of this invention are salts derived from the halogenated diphosphonate esters. The use and preparation of such salts using the compounds prepared by this invention is more fully described in the copending U.S. application of Clarence H. Roy, Novel Compounds, Ser. No. 266,055, filed Mar. 18, 1963, now U.S. Patent No. 3,422,021; and

the invention will hereinafter become apparent to those 3,772,412 Patented Nov. 13, 1973 ICC in U.S. Patent 3,404,178. This application and patent are incorporated herein by reference.

The use of the halogenated diphosphonate esters and phosphonoacetate esters as antiwear and extreme pressure additives in lubricant compositions is disclosed in the copending application of Robert E. Wann, Denzel A. Nicholson, and Ted J. Logan, Lubricant Composition, Ser. No. 762,966, filed Sept. 26, 1968, now U.S. Patent No. 3,579,449. This application is incorporated herein by reference.

The use of unhalogenated diphosphonate esters or salts derived therefrom as builders has not until recently been of substantial interest. Therefore, very little literature is available as to their use as builders, and none regarding the preparation of the halogenated diphosphonates. Nevertheless, there are several methods of replacing an active hydrogen by halogenation, old in the art, by which halo gem-diphosphonate esters might conceivably be synthesized. However, reactions such as direct halogenation of either tetraalkyl esters of methylenediphosphonic acid or its carbanion generally result in low yields and often involve side-reactions hampering the completion of the desired reaction. These reactions have been found to be impractical as they are expensive and the direct halogenation requires elevated temperatures while seldom resulting in yields of greater than 25%.

Using these methods to synthesize the halogenated diphosphonate esters or the halogenated phosphonoacetate esters, it was found that the monohalo derivatives, e.g., the monohalodiphosphonate esters or the monohalo phosphonoacetate esters were diificult to isolate. Typically stoichiometric halogenations produced a mixture of predominantly dihalo and unhalogenated diphosphonate esters and/or phosphonoacetate esters. This unfavorable result is caused by the relatively higher reactivity of the proton on the bridging carbon of the monohalo ester which causes the rapid addition of a second halogen to the monohalogenated molecule in preference to the monohalogenation of the lesser reactive protons on an unhalogenated ester molecule.

Thus, it is an object of this invention to provide a novel process for the preparation of monoand dihalogenated diphosphonate esters and phosphonoacetate esters from the unhalogenated diphosphonate esters and phosphonoacetate eters.

It is also an object of this invention to provide a commercially feasible process for preparing these monoand dihalogenated diphosphonate esters and phosphonoacetate esters which is conducted without difliculty and results in high yields, e.g., greater than about 60% in the case of monohalo esters and greater than about in the case of dihalo esters.

It is a further objective of this invention to provide a rapid, continuous process of preparing monoand dihalogenated diphosphonate esters and monoand dihalogenated phosphonoacetate esters wherein the process is directed largely towards producing either the monoor the dihalo-derivative of said esters.

Still further objects and the entire scope of applicability of the invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and the specific examples, while' indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications Within the spirit and scope of skilled in the art.

SUMMARY OF THE INVENTION It has now been discovered that halogenated diphosphonate esters and halogenated phosphonoacetate esters are prepared by a process which comprises the steps of 3 reacting, with vigorous stirring, an ester selected from the group consisting of:

Compound (A) P 03R:

POsRz R C-Il; and

Pom,

COzR

wherein each R is selected from the group consisting of alkyl, aryl, alkaryl, aralkyl, alkenyl, haloalkyl, haloaryl, haloalkaryl, haloaralkyl, haloalkenyl and nitroaryl groups containing from 3 to about 8 carbon atoms in compounds (A) and (B) and from 5 to 7 carbon atoms in Compound (C) and R is an alkyl, cycloalkyl or aryl group containing from 1 to about 6 carbon atoms, with a hypohalite ion selected from the group consisting of OCl-, OBr, and 01-, in a molar ratio of hypohalite ion to ester of from about 0.7:1 to about 2.5: 1, said reaction being conducted in an aqueous solution containing from about to about 75% added electrolyte, by weight, at a temperature of from about 0 C. to about 100 C., at a pH greater than about 7, and in from about 3 minutes to about 10 hours.

The present invention is valuable in that the reactants and reaction conditions mentioned above can be adjusted in the manner outlined and exemplified below to produce unexpectedly high yields of a large number of halogenated phosphonate compounds.

DESCRIPTION OF THE INVENTION Compound (A) For instance, if the starting ester reactant is Compound (A) and if R is an alkyl group, the starting material is a tetraalkyl methylenediphosphonate and the reaction product is either a monohalogenated tetraalkyl methylenediphosphonate or a dihalogenated tetraalkyl methylenediphosphonate depending on the amount of hypohalite ion employed and the specific reaction conditions. Thus, according to this embodiment of the present invention, the process can be used to prepare such compounds as tetraalkyl monobromomethylenediphosphonate, tetraalkyl dibromomethylenediphosphonate, tetraalkyl monochloromethylenediphosphonate, tetraalkyl dichloromethylenediphosphonate, tetraalkyl monoiodomethylenediphosphonate, tetraalkyl diiodomethylenediphosphonate. The alkyl group forming the ester can be any alkyl group having from 3 to 8 carbon atoms, such as propyl, butyl, pentyl, octyl, or the like.

The monohalogenated tetrahydrocarbyl methylenediphosphonates or dihalogenated tetrahydrocarbyl methylenediphosphonates can be prepared using the process of this invention where the alkyl groups forming the diphosphonate ester in Compound (A) in the above embodiment are replaced by the appropriate hydrocarbyl groups, e.g., where R'is an aryl, alkaryl, aralkyl, alkenyl, haloalkyl, haloaryl, haloalkaryl, haloaralkyl, haloalkenyl, or a nitroaryl group. More specifically, where R is an aryl group such as phenyl, the starting material is a tetraphenyl methylene diphosphonate ester and a monoor dihalogenated tetraphenyl methylene diphosphonate ester is produced by the process of this invention. Similarly, where R is an alkaryl group such as methylphenyl, an aralkyl group such as benzyl, an alkenyl group such as hexenyl, a haloalkyl group such as 3-fluoro-propyl, a haloaryl group such as bromophenyl, a haloalkaryl group such as (chloromethyl)phenyl, a haloaralkyl group such as (chlorophenyl)ethyl, a haloalkenyl group such as -iodopentenyl, and a nitroaryl group such as nitrophenyl, tetramethylphenyl methylenediphosphonate, tetrabenzyl methylenediphosphonate, tetrahexenyl methylenediphosphonate,

Compound (B) Compound (0) tetra(3-fluoropropyl) methylenediphosphonate, tetra (bromophenyl) methylenediphosphonate, tetra[(chloromethyl) phenyl] methylenediphosphonate, tetra[ (chlorophenyl)ethyl] methylenediphosphonate, tetra(5-iodopentenyl) methylenediphosphonate and tetra(nitrophenyl) methylenediphosphonate are the starting materials with the corresponding monoor dihalogenated methylenediphosphonates formed respectively.

Compound (B) By the same token the use of Compound (B) as a starting material leads to the formation of the corresponding monohalogenated alkylidenediphosphonate esters such as As with Compound (A) the alkyl groups above forming the esters in Compound (B), e.g., where R in Compound (B), can be replaced by aryl, alkaryl, aralkyl, alkenyl, haloalkyl, haloaryl, haloalkaryl, haloaralkyl, haloalkenyl, and nitroaryl groups, as disclosed hereinbefore col. 3, line 54, to col. 4, line 8, result in the tetrahydrocarbyl alkylidenediphosphonate esters as the starting materials. These starting materials can be used to form the tetrahydrocarbyl monohalogenated alkylidenediphosphonate esters.

Compound (C) The use of Compound (C) as a starting material with R being an alkyl group leads to the formation of the corresponding monohalogenated and dihalogenated phosph'onoacetate esters such as the trialkyl bromophosphonoacetates, dibromophosphonoacetates, chlorophosphonoacetates, dichlorophosphonoacetates, iodophosphonoacetates, and diiodophosphonoacetates.

In addition the use of Compound (C) with R being an aryl group as a starting material leads to the formation o the corresponding monohalogenated and dihalogenated phosphonoacetate esters, such as, the corresponding triaryl bromophosphonoacetates, dibromophosphonoacetates, chlorophosphonoacetates, dichlorophosphonoacetates, iodophosphonoacetates and diiodophosphonoacetates. Specific examples of the above trialkyl and triaryl starting materials are tripentyl phosphonoacetate, and triphenyl phosphonoacetate. When these trialkyl and triaryl starting materials are used, the tripentyl monoand dibromophosphonoacetates, tripently monoand dichlorophosphonoacetates, tripentyl monoand diiodophosphonoacetates and the triphenyl monoand dibromophosphonoacetates, triphenyl monoand dich10r0phosph0n0 acetates, and triphenyl monoand diiodophosphonoacetates are formed in the process of this invention. As with Compounds (A) and (B) above, other hydrocarbyl groups having from 5 to 7 carbon atoms, similar to those examples given hereinbefore for R on page 6, line 26 to page 7, line 8 forming the esters of Compound (B) and Compound (A), can be used to form the esters of Compound (C), e.g., the trihydrocarbylphosphonoacetates.

q PROCESS CONDITIONS The reaction conditions which should be used to prepare the foregoing compounds are made clear below. The reaction system is a fairly complex one but by adhering to the following discussion, high yields of any of the foregoing compounds can be prepared.

The reaction system involving the preparation of the monoand dihalogenated methylenediphosphonate ester compounds is discussed first. The process for the preparation of the monohalogenated alkylidenediphosphonate ester compounds is similar to the preparation of the dihalogenated methylenediphosphonate esters and is discussed subsequently. The process for the preparation of the monoand dihalogenated phosphonoacetate ester compounds is similar to the process of preparing the monoand dihalogenated methylenediphosphonate ester compounds and is also discussed and illustrated separately below. 1

(a) Preparation of the monohalomethylenediphosphonate ester The embodiment of this invention according to which a monohalo methylenediphosphonate ester is prepared is illustrated by the following equation:

( M,H2O

In the above equation, OX is a hypohalite ion with X being a halogen atom selected from the group consisting of chlorine, bromine and iodine atoms; M is an added electrolyte, as defined hereinafter, and R is as hereinbefore defined. An excess of hypohalite ion tends to carry the reaction on to form the dihalo diphosphonate esters as explained below. It has been discovered that although surprisingly high yields of a monohalogenated product can be obtained using from about 0.7 to as high as about 1.5 moles of hypohalite ion to 1.0 mole of methylenediphosphonate ester, it is preferred for maximum yields that from about 0.90 to about 1.05 moles of hypohalite ion to 1 mole of methylenediphosphonate ester be employed in the present reaction. The reaction may be terminated at this point, as discussed hereinafter, producing surprisingly high yields of the monohalo methylenediphosphonate.

(b) Preparation of the dihalomethylenediphosphonate ester According to a further embodiment of this invention, the above reaction for the preparation of the monohalomethylenediphosphonate esters can be allowed to continue, producing the corresponding dihalomethylenediphosphonate esters. In this embodiment of the invention, the hypohalite ion reacts with the monohalodiphosphonate ester reaction product of Equation I to produce the dihalomethylenediphosphonate ester. To provide sufiicient hypohalite ion to form the dihalomethylenediphosphonate ester-an excess of the hypohalite ion should be used.

It has been discovered that the highest yield of the dihalomethylenediphosphonate ester is obtained by using from about 2.0 to about 2.5'n1oles of hypohalite ion per 1.0 mole of methylenediphosphonate ester. It is preferred that from 2.05 to 2.1 moles of hypohalite ion be used per 1.0 mole of methylenediphosphonate ester in the foregoing reaction to form the dihalomethylenediphosphonate estenThe ratios given above for the preparation of the dihalomethylenediphosphonate ester are basedon the preparation of the dihalomethylenediphosphonate ester from the methylenediphosphonate ester as described by Equation I above and Equation 11 below.

This dihalogenation embodiment of the invention is more fully described by the following equation wherein all terms are as defined in Equation I. 'I'his equation can be considered in conjunction with Equation I have in which the XHC(PO R is the reaction product of Equation I.

R, X and M are as hereinbefore defined.

By the same token, the preparation of the dihalomethylene diphosphonate ester can proceed according to the Equation II reaction sequence involving a monohalomethylenediphosphonate ester obtained from any source, that is, from Equation I or by any other suitable reaction. In this latter event, the highest yields of dihalomethylenediphosphonate ester are obtained by using from about 1.0 to about 1.5 moles of hypohalite per 1.0 mole of monohalomethylenediphosphonate ester and preferably from 1.05 to 1.1 moles of hypohalite per 1.0 mole of monohalomethylenediphosphonate ester. It will be appreciated that dihalomethylenediphosphonates containing mixtures of halogens, e.g., chlorobromomethylenediphosphonate, can be prepared by this second embodiment by an appropriate selection of reactants.

The halogenation reactions of this invention, are normally heterogeneous reactions between two substantially immiscible liquid phases, viz., the diphosphonate ester organic phase and an aqueous phase. The aqueous phase is considered the reaction zone. No added electrolyte is necessary, e.g., no electrolyte other than that present as a part of the hypohalite reactant, in the practice of the process of this invention. However, it is preferred that the aqueous phase contain an electrolyte concentration of from about 0.2% to about 75% by weight obtained either from the hypohalite ion and/or from an added electrolyte. Where an electrolyte is to be added the electrolyte used can be a base such as NaOH or KOH; or a salt, as NaCl, Na CO K2C03, NaNO Na SO K2304, NaC H O and the like or any other compounds of the general class known as electrolytes which are water-soluble and do not react with the hypohalite ion, e.g., the alkali metal borates, carboxylates and phosphonates. Where an electrolyte containing a halide is used, care should be taken that the electrolyte chosen is not a salt of a halide other than that which is to be added to,the diphosphonate ester. If this care is not taken, substitution of halides other than the desired halide, which is being reacted with the diphosphonate ester, could occur as a competing reaction or could result in a mixture of halogenated diphosphonate ester reaction products.

Both reactions I and II are conducted above a pH of 7 at from about 0 C. to about C. The reactions take 'from about 3 minutes to about 10 hours depending upon For the dihalogenation reaction (Equation II above), there is no reason to limit the reaction time and the reation can be conducted as rapidly as desired because the formation step of the monohalogenated product is not controlling. Thus, the dihalogenation reaction can be completed in from about 3 minutes to about 10 hours, depending upon the rate of hypohalite addition.

The hypohalite ion reactant can be added directly to an aqueous solution or can be generated in situ in the aqueous solution such as, for example, by repeated additions of small amounts of the desired halogen such as liquid bromine, chlorine gas, or iodine as a solid or a solution. Suitable hypohalites which can be added direct- 1y include all alkali metal and alkaline earth hypochlorities hypobromites, and hypoiodites. Examples of suitable 7 alkali, metal or alkaline earth metal hypohalites are Ca(OCl) Ca(OBr) KOCl, KOBr, NaOCl, and NaOBr. It is preferred that the hypohalite ions be generated in situ for reasons stated hereinafter.

In the preferred method of producing the monohalogenated diphosphonate ester, a mixture of the aqueous phase and the methylenediphosphonate ester organic phase is stirred vigorously. Rapid stirring is essential as this tends to break the organic phase into tiny discrete glo' bules intermixed with the aqueous phase. This agitation of the mixture is continued, while adding to the reaction mixture a compound capable of providing, in the aqueous solution phase, the necessary concentration of an ion selected from the group consisting of C1", OBr-, and 01-. The term compound here is used in a broad sense to cover both addition of elemental halogen or an alkali or alkaline earth metal hypohalite.

It has been discovered that the solubility of the particular diphosphonate ester employed is important in the process of directing the reaction toward monoor dihalo substitution. The methylenediphosphonate esters are soluble in the aqueous phase reaction zone in the order, methylenediphosphonate esters monohalomethylenediphosphonate esters dihalomethylenediphosphonate esters. The solubility of the methylenediphosphonates decreases with increased halogen substitution. The solubility of each of the diphosphonate esters in the aqueous phase can be substantially increased or decreased, respectively, by decreasing or increasing of the total electrolyte concentration respectively. The solubility of the diphosphonate esters also can be increased or decreased by decreasing or increasing the temperature respectively.

In directing the reaction toward a monohalomethylenediphosphonate product care must be taken to adjust the temperature and the total electrolyte concentration within the limits prescribed herein so that an essential balance is achieved whereby the monohalomethylenediphosphonate ester is essentially insoluble in the aqueous phase reaction zone, but the unhalogenated methylenediphosphonate ester is sufiiciently soluble to allow the reaction to continue. Through the maintenance of such a balance, the monohalomethylenediphosphonate ester which is formed will pass into the organic phase before it is converted further to a dihalomethylenediphosphonate ester. To maintain such a balance and give high yields of the monohalogenated material it is preferred that the aqueous phase should have an electrolyte concentration of from about 9% to about 75% by weight and, preferably an electrolyte concentration of from about 20% to about 65% by weight.

To obtain the monohalo product it is preferable that the hypohalite ion be slowly generated in situ, thereby allowing the monohalomethylenediphosphonate to pass out of the reaction zone without reacting further. To generate the hypohalite ion in situ, the desired halogen may be added directly to the basic aqueous phase. The halogen reacts with water according to the following equilibrium: H O+X :;H++X-+HOX. The base present in the aqueous phase then reacts with HOX to form OX- as follows: HOX+OH-:H O+OX-.

Recovery of the desired monohalogenated methylenediphosphonate ester product can be performed by a cessation of stirring which allows the aggregation of the tiny discrete organic phase globules into one homogenous reacted organic phases. The organic phase can then be readily separated from the aqueous solution and the monohalomethylenediphosphonate ester product extracted from the organic reaction product by methods old in the art, e.g., chromatography, selective extraction and fractional crystallization.

As mentioned previously this invention can be suitably used to produce the dihalomethylenediphosphonate esters. Preparation of dihalodiphosphonate esters in an almost quantitative yield can be achieved by encouraging into the aqueous reaction zone the monohalodiphosphonate ester.

To facilitate this, as indicated above, the temperature can be lowered, the electrolyte concentration can be decreased or both temperature and electrolyte concentration can be adjusted in the manner taught above. It has been discovered that the diphosphonate esters go into solution to a significant extent when the total electrolyte concentration is from 0 to about 30% by weight. It is preferred that the electrolyte be from 0.2% to about 20% by weight in the production of the dihalomethylenediphosphonate esters. A rapid conversion to the dihalomethylenediphosphonate ester occurs, as the monohalomethylenediphosphonate ester is soluble in the aqueous reaction zone. This reaction can be carried to completion in about 3 minutes resulting in yields consistently greater than dihalomethylene diphosphonate ester.

It will be understood, of course, that alternative procedures are within the scope of this invention. For instance, the methylenediphosphonate ester can be added to an aqueous hypohalite solution to produce the same net effect.

(0) Preparation of monohalogenated alkylidenediphosphonate esters Another embodiment of the present invention involves the preparation of a monohalogenated alkylidenediphosphonate ester in addition to the previously-described methylenediphosphonate ester. This preparation requires the use of Compound (B) as described above having the following formula:

Pom, Ii -$41 with R and R having the meaning described hereinbefore.

The preparation of the monohalogenated alkylidinediphosphonate esters is more fully illustrated by the following equation:

(III) wherein R is alkyl, cycloalkyl or aryl radical containing from 1 to about 6 carbon atoms. All other terms are as defined in Equations I and II above.

The same reaction conditions which apply to the dihalogenation of the monohalogenated methylenediphosphonate ester described in detail hereinbefore in connection with Equation II apply also to Equation III. The alkylidenediphosphonate ester starting materials represented by Compound (B) above are much more insoluble in the aqueous phase than are the methylenediphosphonate esters. Thus, it is desirable that the electrolyte concentration be maintained within a range of 0% to about 30%, and preferably towards the lower end of a concentration range of 0.2% to about 20% by weight, in order to encourage the alkylidenediphosphonate esters into the aqueous reaction solution.

(d) Preparation of monoand dihalogenated phosphonoacetate esters Another embodiment of the present invention involves the preparation of monohalogenated and dihalogenated phosphonoacetate esters. This preparation requires the use of Compound (C) as described hereinbefore having the following formula:

POaR: u-c-rr where R has the meaning given hereinbefore.

The preparatlon of the monoand dihalogenated phosphonoacetate esters is more fully illustrated by the following equations:

M, H2O RzPoaomoooR OX- R PO CXHCOOR 011- wherein R, M and X have the meanings given hereinbefore.

The reaction conditions which apply to the monohalogenation of methylenediphosphonate esters described above in detail in connection with Equation I apply equally to Equation IV and the reaction conditions which apply to the dihalogenation of the monohalogenated methylene diphosphonate esters described in detail in connection with Equation II apply equally to Equation V.

In practicing each of the foregoing embodiments of this invention care must be taken that the reaction temperatures are not so high that the hypohalite ion (OX- is converted to the halate ion (X creating a deficiency of hypohalite ion in the reaction mixture. For example, temperatures up to about 50 C. are usually satisfactory for avoidance of the conversion of hypochlorite to chlorate, but are only marginally satisfactory for avoidance of the conversion of hypobromite to bromate. However by generating the hypohalite in situ, the reactions can be conducted at substantially higher temperatures, i.e. over 80 C., as the hypohalite ion reacts with the disphosphonate ester before there is time for it to disproportionate to form the halate ion.

Another temperature consideration is that it must not be so high that it reaches a point at which undesirable ester saponification becomes significant. The temperature at which saponification occurs is governed by the pH of the system which is being used, higher pHs favoring more saponification. Ester saponification to a significantly detrimental degree will occur above about 100 C. when the pH of the system is near neutrality, i.e., from about pH 7 to about pH 9. However, at highly basic pHs saponification will occur to a detrimental degree even at lower temperatures.

Care must also be taken to avoid excessive formation of hypohalous acid in the reaction system. The aqueous reaction medium must be keptbasic enough to sustain the desired hypohalite ion. If the pH of the reaction systern is decreased the equilibrium HOX OX-+H+ will shift to the left, causing the hypohalite ion to disappear due to the formation of hypohalous acid. Consequently, the pH of the reaction system must be kept above about 7 in the case of chlorination, above about a pH of 8 for bromination and above a pH of 10 for iodation. Although the halogenation may be conducted in a reaction solution having a pH as high as about 14, it is preferable for avoidance of ester saponification that the pH of the reaction solution be about 11. Under these conditions,

The tetrahydrocarbyl methylenediphosphonate esters, Compound (A), used as starting materials in this invention can be prepared by reacting a dibromomethane with a trihydrocarbyl phosphite in accordance with the following equation:

where R is as hereinbefore defined. The trihydrocarbyl phosphite in this reaction can be derived from an alcohol 10 and phosphorous trichloride. The dibromomethane is a high temperature reaction product of methane and bromine. A more detailed discussion of the foregoing appears in US. application of Clarence H. Roy, Novel Compounds, Ser. No. 266,055, filed Mar. 18, 1963.

The tetrahydrocarbyl alkylidenediphosphonate esters Compound (B) used as starting materials in this invention can be prepared by reacting a gem-alkyldibromide, R CHBr with a trihydrocarbyl phosphite in accordance with the following equation:

wherein R and R are hereinbefore defined. The trihydrocarbyl phosphite can be obtained as before and the gem-alkyldibromides are well-known and commonly available.

The trihydrocarbyl phosphonoacetate esters, Compound (C), used as starting materials in this invention can be prepared by reacting a trihydrocarbyl phosphite with bromoacetic acid ester in accordance with the following equation:

wherein R is as hereinbefore defined. The bromoacetate ester used above is well-known and commercially available.

The process of this invention is illustrated by the following examples but is not limited thereto.

EXAMPLE I Tetra-iso-propyl monoiodomethylenediphosphonate A 9% K CO aqueous electrolyte solution was prepared by dissolving 25 g. of K CO in 250 cc. of water. To this was added 16 cc. (0.05 mole) of tetra-iso-propyl methylenediphosphonate. The pH of this solution was about 11.7. A second solution was prepared, consisting of 13 g. (0.05 mole) of I dissolved in 50 cc. of water containing 20 g. of KI. The second solution was added slowly to the first solution with vigorous stirring and the temperature maintained at 15 C. When about half the second solution had been added, the pH had dropped to about 10.6 where the reaction nearly stopped; 10 g. of KOH dissolved in 25 cc. of water was added to the reaction mixture to readjust the pH near 12. Addition of the second solution continued with a total addition time of about 2 hours. The final reaction mixture contained a total of 17% by weight electrolyte and had reacted equimolar amounts of 01- and tetra-iso-propyl methylenediphosphonate.

The ester product was recovered by several chloroformwater extractions, and the excess chloroform removed by evaporation. The product weighed 23 g. Using a nuclear magnetic resonance spectrometer, a P N.M.R. analysis was made indicating 22% of the product was tetra-isopropyl methylenediphosphonate ester, 61% was tetra-isopropyl monoiodomethylenediphosphonate ester and 17% was tetra-iso-propyl diiodomethylenediphosphonate ester.

A higher yield of tetra-iso-propyl monoiodomethylenediphosphonate ester is obtained if a higher electrolyte concentration is used, e.g., 20-65% instead of the 917% concentration actually used.

EXAMPLE II Tetra-iso-propyl monobromomethylenediphosphonate A 53% K 00 solution was prepared by dissolving 170 g. of K CO in cc. of water resulting in a solution having a pH of about 12. To this solution was added 33 cc. (0.1 mole) of tetra-iso-propyl methylenediphosphonate. The two immiscible liquids were stirred vigorously and 5 cc. of Br dissolved in 25 cc. of heptane was added dropwise over a 2-hour period with the temperature maintained at 40 C. The Br added will form 0.1 mole of OBr' in situ, thus the OBr and tetra-iso-propyl methylenediphosphonate were reacted in a one to one molar ratio.

The ester product was separated from the electrolyte solution by several chloroform-water extractions. The product was recovered from the chloroform solution by evaporating the solvent. The final product weighed 40 g. and by P N.M.R. analysis was 32% tetra-iso-propyl methylenediphosphonate ester, 57% tetra-iso-propyl monobromomethylenediphosphonate ester and 11% tetraiso-propyl dibromomethylenediphosphonate ester.

Similarly, the iodine may be substituted for the bromine in the above reaction to prepare tetra-iso-propyl monoiodomethylene diphosphonate.

EXAMPLE III Tetra-iso-propyl monochloromethylenediphosphonate A hypochlorite solution was prepared by dissolving 100 g. of NaOH in 213 cc. of a 5.25% NaOCl solution (0.15 mole NaOCl) containing an equimolar amount of NaCl and having a pH greater than 13. This solution had an electrolyte concentration of about 50%. To this was added 100 cc. of CHCl and the two immiscible liquids heated to 50 C. With rapid stirring, 33 cc. (0.1 mole) of tetra-isopropyl methylenediphosphonate was added to this solution over a 10-minute period. The temperature was maintained between 45 C. and 60 C. during the reaction.

The reaction product was recovered by adding an additional 50 cc. of CHCl and 50 cc. of CH CH OH, causing the system to separate into two liquid layers. The CHCl layer was removed, extracted with 250 cc. of water, and the solvents removed by vacuum evaporation. The product remaining after evaporation weighed 36 g. and by P N.M.R. analysis showed 66% tetra-iso-propyl methylenediphosphonate ester, 13% tetra-iso-propyl monochloromethylenediphosphonate ester and 21% tetra-iso-propyl dichloromethylenediphosphonate ester.

A higher yield of tetra-iso-propyl monochloromethylenediphosphonate ester results if gaseous C1 is fed into a system containing tetra-iso-propyl methylenediphosphonate ester slurried in aqueous 55% K CO' solution. The tetraiso-propyl monochloromethylenediphosphonate ester proportional yield may also be increased by reducing the molar ratio of hypochlorite ion to tetra-iso-propyl methylenediphosphonate ester from the 1.5:1 actually used, to 1:1 or slightly below.

EXAMPLE IV Tetra-iso-propyl diiodomethylenediphosphonate The following solutions are prepared:

(1) 41.4 g. K CO dissolved in 400 cc. H electrolyte solution);

(2) 25 g. I dissolved in 150 cc. of water containing 25 g. of KI-will form 0.1 mole of 01- in situ;

(3) 25 g. of KOH dissolved in 50 cc. of water. To solution No. 1 is added 16 cc. (0.05 mole) of tetra-isopropyl methylenediphosphonate. Then, with the temperature maintained at C. and with vigorous stirring, solution No. 2 is added dropwise to the foregoing solution containing tetraiso-propyl methylenediphosphonate with solution No. 3 being added as needed to maintain the pH of the reaction mixture near pH 11. After about one third of solutions No. 2 and No. 3 had been added, 100 cc. of chloroform is added to retard the formation of solid tetraiso-propyl -diiodomethylenediphosphonate ester. The addition of solutions No. 2 and No. 3 are complete in about one hour. The reactant ratio used is 2:1 OI to tetra-isopropyl methylenediphosphonate. A solid product was filtered off and washed with water. This product weighed g. and was found to be 100% tetra-iso-propyl diiodomethylenediphosphonate ester by P N.M.R. analysis.

EXAMPLE V Tetra-iso-propyl dibromomethylenediphosphonate A 294.5 g. sample of mixed esters having 0.6 mole of replaceable hydrogen, which was 65% tetra-iso-propyl methylenediphosphonate, 11% tetra-iso-propyl monobromomethylenediphosphonate ester, and 27% tetra-isopropyl dibromomethylenediphosphonate ester, was added to 1500 cc. of a 15% NaOH solution having a pH of greater than 13. To this solution, with vigorous stirring, 77 cc. of -Br was added at 25 C. over a 30-minute period. The amount of Br used was sufficient to produce OBr- (0.8 mole) in 25% excess of what would be needed to convert the mixed esters to tetra-iso-propyl dibromomethylenediphosphonate. At this point a sample of the ester mixture was removed for P N.M.R. analysis and found to be tetra-iso-propyl dibromomethylenediphosphonate ester. The reaction mixture was digested for 1 hour at 0 to 5 C., then extracted thoroughly with chloroform-water. The product was recovered by evaporating the chloroform washings. A yield of 336 g. of tetraiso-propyl dibromomethylenediphosphonate ester was obtained.

EXAMPLE VI Tetra-iso-propyl dichloromethylenediphosphonate To 505 cc. of tetra-iso-propyl methylenediphosphonate (1.5 moles) was added 4200 cc. of a 5.25 NaOCl solution (3.2 moles of OC1-). The pH of the NaOCl solution was 11.5 due to hydrolysis and the solution contained an equimolar amount of NaCl (4.1% of electrolyte solution). During addition of the N aOCl solution, the system was stirred vigorously and an ice bath used to maintain the temperature between 25 to 30 C. during the 30 minutes of addition time. The final 001- to tetra-isopropyl methylenediphosphonate ratio was 2.1 to 1. The system was stirred an additional 30 minutes at 30 C., then allowed to stand until the two immiscible liquids separated into layers. The organic layer was drawn off and the residual water removed by vacuum evaporation. The dried product weighed 644 g. and was 100% tetra-iso-propyl dichloromethylenediphosphonate by P N.M.R. analysis.

Results similar to those in the examples can be obtained using many other electrolytes, e.g., NaCl, KCl, K 80 K CO NaC H O and NaNO etc. Similarly, other tetraalkyl diphosphonate esters may be used, e.g., tetraoctyl, tetrahexyl, tetrabutyl, etc. In addition other tetrahydrocarbyl diphosphonate esters may be substituted for the tetra-iso-propyl dichloromethylenediphosphonate used above to prepare the corresponding tetrahydrocarbyl dichloromethylenediphosphonate esters, e.g.,

tetra(methyl)phenyl methylenediphosphonate, tetrapentyl methylenediphosphonate,

tetrapentyl methylenediphosphonate,

tetra( 3-chloro propyl methylenediphosphonate, tetra(bromo)phenyl methylenediphosphonate,

tetra[ (chloromethyl) phenyl] methylenediphosphonate, tetra[ (chlorophenyl)methyl] methylenediphosphonate, tetra(S-iodopentenyl) methylenediphosphonate, and tetra(nitrophenyl) methylenediphosphonate.

EXAMPLE VI'I Tetra-iso-propyl pentane-l-chloro-l, l-diphosphonate A g. sample of a 2 to 1 mixture of tetra-iso-propyl pentane -1,1-diphosphonate (0.254 mole) to tetra-isopropyl methylenediphosphonate (0.127 mole) was added to 1180 mls. of a 5.25% NaOCl solution (0.89 mole of OCl-). The 5.25% NaOCl solution contained an equimolar amount of NaCl (4.1% electrolyte solution) and had a pH of about 11.5 due to hydrolysis. This reaction system was stirred vigorously for one hour and forty minutes at room temperature, and then, was allowed to stand until the two immiscible liquids separated into layers (aqueous and ester phase). The organic phase was removed by chloroform extraction. The dried product was found to be 24% tetra-iso-propyl pentane-1,1-diphosphonate. 45% tetra-isopropyl pentane-1-ch1oro-1,1-di- 13 phosphonate, and 31% tetra-iso-propyl dichloromethylenediphosphonate.

Results similar to those in this example can be obtained using other alkylidenediphosphonate esters; e.g., tetra-iso-propyl ethane-1,1 diphosphonate, tetra-iso-propyl propane-1,l diphosphonate, tetra-iso-propyl butane-1,1-diphosphonate, tetra-iso=propyl phenylmethane-l,l-diphosphonate, tetra-iso-propyl hexane-1,1-diphosphonate, etc. Similarly, other hypohalites may be used in the present reaction; e.g., OI and OBr-. Similarly other alkyl groups may be substituted for the iso-propyl group, e.g., butyl, iso-butyl, hexyl, and octyl in the above reaction.

A higher yieldof tetra-iso-propyl pentane-1-chloro-l,1- diphosphonate is obtained if a lower temperature is utilized than that actually used. This would cause the ester to be more soluble in the aqueous reaction phase.

EXAMPLE VIII Tripentyl dibromophosphonoacetate Tripentylphosphonoacetate, 17.2 g. (0.044 mole) was added to a 2-liter flask containing 0.098 mole of NaOBr (about 12% excess) in an aqueous system containing 500 cc. of water at a pH of about 11. The mixture was reacted for 10 min. at to C. with vigorous stirring. Several chloroform water extractions were made and the combined extracts dried over anhydrous sodium sulfate. The extractions were filtered to remove the sodium sulfate, and the excess. chloroform was removed by evaporation. A colorless liquid was obtained and was identified as the tripentyl ester of dibromophosphonoacetic acid having the following analysis:

Calcd. C, 40.02; H, 6.5; P, 6.1; Br, 31.5; mol. wt. 508.

Found: C,40.5;-H, 6.8; P, 5.7; Br, 36.0; mol. wt. 500.

NaOI can be substituted for the NaOBr used in the above reaction to prepare the tripentyl diiodophosphonoacetate ester. Similarly other trihydrocarbyl phosphonoacetate esters can be substituted for the tripentyl phosphonoacetate ester used above to prepare the corresponding trihydrocarbyl dibromophosphonoacetate esters, e.g.,

triphenyl phosphonoacetate, tri(methyDphenyl phosphonoacetate, tripentyl phosphonoacetate, tri(3-chloro)propyl phosphonoacetate, tri(bromo)phenyl phosphonoacetate,

tri[ (chloromethyl)phenyl] phosphonoacetate, tri (chlorophenyl methyl] phosphonoacetate, tri(5-iodopentenyl) phosphonoacetate, and tri(nitrophenyl) phosphonoacetate.

EXAMPLE IX Tri(2-methyl-1-butyl) dichlorophosphonoacetate) Tri(2-ethy1-l-butyl)phosphonoacetate, 1 mole (380 g.), is placed in a reaction flask with 4 moles (160 g.) of sodium hydroxide in 500 ml. of water at 0 C. and stirred vigorously. Chlorine, 2 moles (142 g.), are then bubbled into the two phase system. After the chlorine addition, the mixture is stirred for additional minutes at 0 C. At this time the layers are separated and the aqueous solution is extracted three times with carbon tetrachloride. The carbon tetrachloride extractions are combined with the original organic layer and dried over anhydrous sodium sulfate for several minutes. The product layer is filtered and the carbon tetrachloride is removed by evaporation. The product, tri(Z-methyl-lbutyl)dichlorophosphonoacetate is obtained in a 80- 100% yield at about 90% purity.

EXAMPLE X Tri(iso-pentyl)monochloro phosphonoacetate Tri(iso-pentyl)phosphonoacetate, 1 mole (318 g.), is placed in a reaction flask at 25 C. The phosphonoacetate in the reaction flask is stirred vigorously during the addition of 1 mole of sodium hypochlorite in a water solution 14 (74 g. of sodium hypochloride, 200 cc. of water) to which 200 g. of K CO has been added. After the addition of the sodium hypochlorite is complete the mixture is stirred at 25 C. for an addition 10 minutes. At this time two layers had formed. The water layer is extracted three times with carbon tetrachloride. The carbon tetrachloride extracts are combined with the original product layer, dried over anhydrous sodium sulfate for 15 minutes, filtered, and the carbon tetrachloride removed by evaporation. The product, tri(iso-pentyl)monochlorophosphonoacetate, is obtained in about -100% yield and is about 60% pure.

Other trihydrocarbyl phosphonoacetate esters can be substituted for the tri(iso-pentyl) phosphonoacetate used in the above example to prepare the corresponding trihydrocarbyl monochlorophosphonoacetate esters, e.g., triphenyl phosphonoacetate, tri(methyl)phenyl phosphonoacetate, triphentyl phosphonoacetate, tri(3-chloro) propyl phosphonoacetate, tri(bromo)phenyl phosphonoacetate, tri[(chlorornethyl)phenyl] phosphonoacetate, tri[(chlorophenyl)methyl] phosphonoacetate, tri(S-iodopentyl) phosphonoacetate, an dtri(nitrophenyl) phosphonoacetate.

EXAMPLE XI Tri(2-ethyl-1-pentyl)monobromophosphonoacetate Tri(2-ethyl-l-pentyl)phosphonoacetate, 1 mole (434 g.), is placed in a reaction flask at 25 C. The phosphonoacetate is stirred vigorously as a sodium hypobromite solution (1 mole of sodium hypobromite in 300 cc. of water containing g. of Na SO is added slow- 1y. After the addition of the hypobromite, the mixture is stirred at 25 C. for an additional 10 minutes. At this time two layers are formed and the water layer extracted three times with carbon tetrachloride. The carbon tetrachloride extracts are combined with the original product layer, dried over anhydrous sodium sulfate for 15 minutes, filtered and the carbon tetrachloride removed by evaporation. The product, tri(Z-ethyl-l-pentyl) monobromophosphonoacetate, is obtained in about 80 to yield and is about 60% pure.

Sodium hypoiodite can be substituted for the sodium hypobromite used in the above example to prepare tri (Z-ethyl-l-pentyl)monoiodophosphonoacetate.

The halogenated esters prepared in Examples I to XI above are useful as extreme pressure additives in lubricant compositions when the halogenated esters are used in a Kendall base SAE 20 mineral oil at a 5% level.

The dibrominated and diiodated gem-methylenediphosphonate esters having from 3 to 8 carbon atoms (e.g., tetraheptyl diiodomethylenediphosphonates and tetrabutyl dibromomethylenediphosphonates as prepared in Example IV using tetraheptyl methylenediphosphonate and in Example V using tetrabutyl methylenediphosphonate, respectively, for the tetra-iso-propyl methtylenediphosphonate used in these examples), are novel compounds and exhibit excellent efiicacy as extreme pressure additives when used in a Kendall base SAE 20 mineral oil at a 5% level. This efiicacy was surprising in view of the performance of the corresponding dichloro compounds. The dichloromethylenediphosphonate esters having from 7 to 8 carbon atoms, e.g., as prepared in Example V-I using tetraheptylor tetraoctyl methylenediphosphonate for tetra-iso-propyl methyleuediphosphonate, are novel compounds having utility as anti-wear additives when used in a Kendall base SAE 20 mineral oil at a 5% level. The tetraheptyl and tetraoctyl monochloro-, monobromoand monoiodo-methylenediphosphonate esters having 7 to 8 carbon atoms, prepared according to the procedure of Examples III, II and I, respectively, are novel compounds having utility as anti-wear additives in lubricant compositions when used in a Kendall base SAE 20 mineral oil at a 5% level.

The foregoing description has been presented describing certain operable and preferred embodiments of the formula CH: POal: I :l I CHCH3 z 2. A halogenated gem-diphosphonate ester having the formula OH: PO3[ I CHCH3 a I-C I CH3 PO: A:

H-CH: z

3. A process of forming halogenated ester compounds which comprises reacting, with vigorous stirring, an ester selected from the group consisting of:

Compound (A) P 03R: H-C-H;

PJ-C-H; and IiOaRn Compound (B) (502R wherein each R is selected from the group consisting of alkyl, unsubstituted aryl, alkaryl, aralkyl, alkenyl, haloalkyl, haloaryl, haloalkaryl, haloaralkyl, haloalkenyl, and nitroaryl groups containing from 3 to about 8 carbon atoms in Compounds (A) and (B) and from 5 to about 7 carbon atoms in Compound (C) and R is an alkyl, cycloalkyl, or aryl group containing from 1 to about 6 carbon atoms, with a hypohalite ion selected from the group consisting of OCl, OBr, and OI" in a molar ratio of hypohalite to ester of from about 0.7 :1 to about 2.5 :1, said reaction being conduted in an aqueous solution containing from about 0% to about 75% by weight of an added electrolyte selected from the group consisting of dissociable bases and neutral and basic salts which are not reactive with hypohalite, provided however that said electrolyte shall not be a salt of a halogen other than the halogen present in the hypohalite being utilized in the process, at a temperature of from about 0 C. to about 100 C., at a pH greater than about 7, and in from about 3 minutes to about 10 hours.

4. The process of claim 3 wherein about 1 mole of Compound (A) is reacted with from about 2.0 to about 2.5 moles of hypohalite and wherein the aqueous solution contains from about 0% to about 30% electrolyte by weight.

5. The process of claim 4 wherein the aqueous solution contains from about 0.2% to about 20% electrolyte by weight, wherein the molar ratio of hypohalite to ester Compound (C) is from about 2.05 to about 2.1, and wherein the pH is about 11. I

6. The process of claim 5 wherein the hypohalite is 001 and the ester is the tetraisopropyl ester of Compound (A).

7. The process of claim 3 wherein about 1 mole of Compound (A) is reacted with from about 0.7 to about 1.5 moles of hypohalite and wherein the aqueous solution contains from about 9% to about 75 by weight electrolyte.

8. The process of claim 7 wherein the aqueous solution contains from about 20% to about electrolyte by weight, wherein the molar ratio of hypohalite to ester is from about 0.9 to about 1.05, and wherein the pH is about 11.

9. The process of claim 3 wherein about 1 mole of Compound (B) is reacted with from about 0.7 to about 1.5 moles of hypohalite and wherein the aqueous solution contains from about 0%, to about 30% electrolyte by weight.

10. The process of claim 9 wherein the aqueous solution contains from about 0.2% to about 20% electrolyte by weight, wherein the molar ratio of hypohalite to ester is from about 0.9 to about 1.05, and wherein the pH is about 11.

11. The process of claim 3 wherein about 1 mole of Compound (C) is reacted with from about 0.7 to about 1.5 moles of hypohalite and wherein the aqueous solution contains from about 9% to about by Weight electrolyte.

12. The process of claim 11 wherein the aqueous solution contains from about 20% to about 65% by weight electrolyte, wherein the molar ratio of hypohalite to ester is from about 0.9 to about 1.05 and wherein the pH is about 11.

13. The process of claim 3 wherein about 1 mole of Compound (C) is reacted with from about 2.0 to about 2.5 moles of hypohalite and wherein the aqueous solu tion contains from about 0% to about 30% by weight electrolyte.

14. The process of claim 13 wherein the aqueous Solution contains from about 0.2% to about 20% by weight electrolyte, wherein the molar ratio of hypohalite to ester is from about 2.05 to about 2.1 and wherein the pH is about 11.

References Cited UNITED STATES PATENTS 3,422,021 1/ 1969 Roy 260932 X 3,471,552 10/1969 Budnick 260932 X OTHER REFERENCES Groggins: Unit Processes in Organic Synthesis,

McGraw-Hill, New York, 5th ed. (1958), pp. 206-208 and 250.

Bunyan et al.: J. Chem. Soc. (1962), pp. 2953-2958.

LEWIS GOTTS, Primary Examiner R. L. RAYMOND, Assistant Examiner US. Cl. X.R. 

